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Oxygen vacancy‐induced microstructural changes of annealed CeO 2− x nanocrystals
Author(s) -
Aškrabić S.,
DohčevićMitrović Z.,
Kremenović A.,
Lazarević N.,
Kahlenberg V.,
Popović Z. V.
Publication year - 2012
Publication title -
journal of raman spectroscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.748
H-Index - 110
eISSN - 1097-4555
pISSN - 0377-0486
DOI - 10.1002/jrs.2987
Subject(s) - nanocrystalline material , raman spectroscopy , materials science , crystallite , annealing (glass) , nanocrystal , vacancy defect , oxygen , ionic conductivity , microstructure , crystallography , analytical chemistry (journal) , nanotechnology , metallurgy , chemistry , optics , electrode , electrolyte , physics , organic chemistry , chromatography
Abstract Nanocrystalline ceria (CeO 2 ) is known for its ionic conductivity and oxygen storage properties, which depend on the presence of oxygen ion vacancies. The vacancies cause several important changes in CeO 2 involving microstrain, electronic structure, magnetic properties, etc. In this article, we focus our attention to the microstructural changes of nanocrystalline CeO 2− x annealed at different temperatures in the range 200–500 °C. Structural and vibrational properties were investigated by X‐ray diffraction and Raman spectroscopy. It was observed that the content of oxygen vacancies changed significantly with increasing annealing temperature, which plays an important role in the observed microstructural changes of the annealed samples. We demonstrate that the observed microstrain changes, because of variable defect content, dominate over the crystallite size effect. This finding is opposite to the conclusions made by several other authors. A new mode, classified as a probable surface mode, was observed in the Raman spectra at ∼480 cm −1 , the appearance of which can be explained by the large defective structure and disorder in the ceria lattice. Copyright © 2011 John Wiley & Sons, Ltd.